Fibre-optic probe hydrophone for ultrasonic and shock-wave measurements in water

Abstract

Aimed at lithotripter acoustic output measurements, a new fibre-optic probe hydrophone overcomes most of the problems involved with the use of piezoelectric hydrophone technology in non-linear ultrasonic and shock-wave fields. The fibre-optic principle allows for extremely wide bandwidth (larger than 1 GHz) and superior electromagnetic shielding. Contrary to hitherto existing hydrophones a high cavitation threshold at the water-silica interface provides undistorted detection of strong rarefractional pulse pressures. Considering pure compression there is good agreement between maximum pulse pressure derived from fibre-optic hydrophone theory and the corresponding amplitudes obtained from acoustically calibrated PVDF membrane and needle hydrophones.